SEISMOLOGY AND GEOLOGY ›› 2014, Vol. 36 ›› Issue (4): 964-975.DOI: 10.3969/j.issn.0253-4967.2014.04.003

• CONTENTS • Previous Articles     Next Articles

GAS PERMEABILITY AND KLINKENBERG EFFECT OF FAULT ROCKS

DUAN Qing-bao, YANG Xiao-song, CHEN Jian-ye   

  1. State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China
  • Received:2014-09-11 Online:2014-12-30 Published:2015-01-07

断层岩气体渗透率及Klinkenberg效应

段庆宝, 杨晓松, 陈建业   

  1. 中国地震局地质研究所, 地震动力学国家重点实验室 100029
  • 通讯作者: 杨晓松,研究员,E-mail:xsyang@ies.ac.cn
  • 作者简介:段庆宝,男,1986年生,2010年毕业于中国地质大学(北京)资源勘查工程(固体矿产)专业,现为中国地震局地质研究所在读博士研究生,主要研究方向为高温高压岩石物理实验及相关工作,电话:010-62009010,E-mail:duan_qingbao@126.com.
  • 基金资助:

    地震动力学国家重点实验室自主研究课题(LED2010A03)、国家科技支撑计划"汶川地震断裂带科学钻探"(WFSD09)课题和中国地震局地震行业科研专项(200808012)共同资助.

Abstract:

The nitrogen gas permeabilities of fault rocks were measured under confining pressure ranging from 4 to 40MPa. At each confining pressure step, we changed the upstream pressure several times and measured the permeability. The measured gas results were then corrected by Klinkenberg's equation. Relationship between slippage factor b and intrinsic permeability kl can be described by a power law correlation expressed as b=0.004 6kl-0.476. Compared with sedimentary rocks, the gas slippage effect of fault rocks is stronger, which should not be ignored when using gas as a medium for permeability experiments. The relationship between gas permeability, intrinsic permeability and pore pressure is expressed as kg/kl=1+(0.009 2kl-0.476)/(Pu+Pd). Results show that the lower the permeability of rocks is, the stronger the Klinkenberg effect is. Additionally, the slippage effect decreases as pore pressure increases. For the relative permeable (10-15m2~10-18m2) samples, their gas permeabilities are almost identical to intrinsic permeabilities under relative higher pore pressure condition(higher than 4MPa). However, for the ultra-low permeable (10-22m2~10-20m2) samples, it's difficult to avoid the slippage effect although under high pore pressure condition. The intrinsic permeability of fault gouge samples ranges between 4.54×10-19m2 and 2.43×10-17m2, and those of the breccia samples are higher by 1~2 orders of magnitude which range between 2.25×10-17m2 and 7.94×10-16m2. These results demonstrate that the permeability structure of Wenchuan earthquake fault zone is characterized by a low permeable fault core and relative higher permeable damaged zone. The fault zone has the characteristics of low permeability for thermal pressurization.

Key words: fault rocks, Klinkenberg effect, gas permeability, intrinsic permeability, Wenchuan earthquake

摘要:

在围压2~40MPa变化范围内, 以恒流法多次变化上游压力测量了以断层岩为主的样品的气体(N2)渗透率, 将实验结果进行了Klinkenberg效应校正.对实验数据的拟合分析表明, 滑脱因子b值与绝对渗透率kl存在b=λkl-d形式的幂律关系, 断层岩符合b=0.004 6kl-0.476 的变化关系.与沉积岩相比, 断层岩的气体滑脱效应更强, 采用气体测量渗透率时, 其滑脱效应不能忽略.断层岩气体渗透率和绝对渗透率与测量所用的孔隙压力间的关系为kg/kl=1+(0.009 2kl-0.476)/(Pu+Pd).结果表明样品渗透率越低, 滑脱效应越强, 提高孔隙压力, 滑脱效应逐渐减小;对于高渗(10-15m2~10-18m2) 的样品, 高孔隙压力下(4MPa以上)的气体渗透率与绝对渗透率基本一致, 对于超低渗(10-22m2~10-20m2)的样品, 即使提高孔隙压力亦很难避免滑脱效应.在40MPa有效压力下断层泥样品的绝对渗透率为4.54×10-19m2~2.43×10-17m2, 角砾岩的绝对渗透率较断层泥高出1~2个数量级, 为2.25×10-17m2~7.94×10-16m2, 表明汶川地震断层带具有核部低、破碎带高的渗透结构, 断层带核部具备热压作用发生所要求的低渗条件.

关键词: 断层岩, Klinkenberg效应, 气体渗透率, 绝对渗透率, 汶川地震

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